Investigation of the relationship between peripheral neuropathy and vascular disease of the lower limb in patients with diabetes mellitus by ultrastructural examination of biopsy tissue and an experimental animal model. An electron microscopic study will be made of the innervation of arteries of the lower limb in patients with diabetes mellitus. Pathological lesions of these nerves will be examined at different stages during the diabetic patients' disease. An ultrastructural study will also be made of the effect of surgical lumbar sympathectomy on the progression of diabetic vascular disease in the lower limb where such a procedure is clinically mandated. In addition a Chinese hamster diabetic mutant which is a useful model of human diabetic neuropathy will be employed in an ultrastructural study of the sequence of events detectable during the progress of the peripheral neuropathy and the possibly related pathological changes in lower limb arteries. Surgical sympathectomy, comparable to the procedure used clinically in human diabetics, will be performed on both the diabetic hamsters and on non-diabetic control hamsters. The subsequent pathological changes in the lower limb nerves and arteries will also be ultrastructurally examined. An attempt will be made to correlate data obtained from the animal model with that obtained from the study of human biopsy material.